1. Field of the Invention
This invention relates to fluidic angular rate sensors and more particularly to improvements in the mechanical and electrical construction thereof.
2. Description of the Prior Art
Fluidic angular rate sensors known to the art are typified by those disclosed in U.S. Pat. Nos. 3,587,328, to Schuemann, and 3,626,765 to Moore et al. In fluidic angular rate sensors, a jet or stream of a suitable fluid, such as an inert gas, is provided by pressurized gas passed through a nozzle, the jet of gas being directed toward a pair of temperature-sensitive resistive elements which are differentially cooled by the jet whenever the jet is moved (such as in angular rotation) in a plane of sensitivity. The sensing elements are typically fine tungsten wires disposed on opposite sides of the centerline of the nozzle boresight. In the Schuemann patent, a vibrating diaphragm entrainment pump, in which the diaphragm is a piezoelectric crystal bimorph, provides the pressurization of the gas.
Fluidic angular rate sensors of this type have no moving parts except the vibrating diaphragm, and no rotating parts whatsoever. They are therefore theoretically capable of low cost manufacture, short start up time, and reliable operation after a long shelf life or storage period. However, the difficulty in manufacture and alignment of such devices, together with variations in operating characteristics over their life times and over variable temperature ranges, have rendered their utility less than complete. Low cost production is not achieved to an adequate extent due to inability for production line re-working of bad units, caused in part by the aggregate of variations in manufacture, in turn caused by numerous custom fittings, alignments and calibrations required in making each unit.